<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
var a = 10
var obj = {
a: 20, say: () => {
console.log(this.a)
}
}
obj.say()
var anotherObj = { a: 30 }
obj.say.apply(anotherObj)

// 10*2


  </script>
</body>
</html>